A Minnesota family is trying to force a New Jersey drug company to give their son an experimental drug for a fatal form of muscular dystrophy, saying he'll die without it.

The boy's mother, Cheri Gunvalson, who helped persuade Congress to significantly boost spending to find a cure for the disease, filed a lawsuit along with her husband and son in federal court in New Jersey this week.

Jacob Gunvalson, 16, suffers from Duchenne muscular dystrophy, a genetic, degenerative disease that mostly affects young boys. Typically, those who suffer from it die in their 20s because of weakness in their heart and lung muscles. There is no known cure, but the Gunvalson family believes the experimental drug holds hope.

The family claims that PTC Therapeutics of South Plainfield, N.J., repeatedly promised them Jacob would have access to the drug, known as PTC124, but then broke its word. The company denied ever making that assurance.

Jacob, who lost his ability to walk about a year ago, said in an interview that he thought he was going to get the drug many times.

"To think you can get help, and then just in the last second it's pulled out — that's like getting your whole future hopes and all that smashed," he said Thursday.

Jacob hopes to one day become a psychiatrist or psychologist to help people facing "tough times."

"But it takes a lot of schooling to get done with that," he said, "and I don't know how much longer I have."

Chip Baird, PTC Therapeutics' chief financial officer, said the company sympathizes with the Gunvalsons and other families suffering from the disease, but that PTC has always communicated with the Gunvalsons "in a clear and consistent manner."

In 2001, Cheri Gunvalson teamed with the late Sen. Paul Wellstone, D-Minn., for passage of the MD CARE Act, which increased federal funding to study the disease. The legislation established several "centers of excellence" — since renamed "Wellstone Centers" — for muscular dystrophy research.

The family claims the company discouraged the Gunvalsons from enrolling Jacob in a preliminary, 28-day trial in 2005, saying it wouldn't hurt his chances of getting into a later study. It then used his absence from that original trial as a reason to disqualify him from a current study.

Jacob is also ineligible for another study because patients have to be able to walk to participate.

PTC's Baird said the family opted not to participate in the clinical trial, but said the company will look for future opportunities once the current trials are over. The Gunvalsons say Jacob will probably be dead by then.

The Gunvalsons, who filed suit on Wednesday, say they want access to the drug through a "compassionate use exception," such as a single-patient study. Jacob's physician says he's willing to do a study but needs the company to provide the drug.

Dr. Richard S. Finkel, the principal investigator on the 28-day trial and director of the neuromuscular program at Children's Hospital of Philadelphia, said there was not enough safety data to make such an exception.

"I realize these parents are all desperate and we as physicians are as well," he said. "We are in this together with the parents. But we have the burden of having to consider the safety of our patients first, particularly when that patient's a child."

The Food and Drug Administration has agreed to fast-track PTC124, but a best-case scenario would be approval in 2011, Finkel said.

On Thursday, Genzyme Corp., a biotechnology company based in Cambridge, Mass., and PTC Therapeutics announced an exclusive global deal to develop PTC124. Under the agreement, PTC will commercialize the drug in the U.S. and Canada, with Genzyme commercializing the treatment in all other countries. Genzyme will make an upfront payment of $100 million to PTC, which also is eligible for up to $337 million in potential milestone payments.